“When have I done enough base training and when should I move on to the build phase?”  “Am I getting what I need from my base training, or am I wasting my time?”. If you’re looking to improve your performance this season, then you should be seeing progressive improvements in your base phase.  Use the below powerful metrics to accurately answer those questions for yourself. You will need to be at least using a GPS device and a reliable heart rate strap (chest strap preferred):

  1. Aerobic Efficiency Factor (EF) is a metric that is a good measure of your aerobic fitness.  For a given workout, it’s equal to your normalized pace or power divided by average heart rate (EF = NP / HRavg). As your basic aerobic fitness increases, you should see your EF value consistently increase from workout to workout (for ones in your aerobic Z1-Z2).  If it’s decreasing or staying the same over the course of a couple weeks for aerobic workouts or aerobic sections of workouts in Z1-2, you need to look at your training and potentially modify if you want to have an effective base phase.
  2. Cardiac Drift, or Decoupling (Pa:HR or Pw:HR) is a measure of aerobic economy on a run or ride.  It’s equal to the ratio of pace to heart rate or power output to heart rate.    At aerobic intensities (Z2), your goal is to minimize how much your HR drifts upwards over time.  Too much rise over time means you are not as aerobically fit as you need to be for a target distance.

Real EF examples in training

Example chart of bad Efficiency Factor
Example chart of good Efficiency Factor

Exactly how to find the answer to “How much base training do I need?”

In TrainingPeaks

It’s easy to find your EF and cardiac drift (decoupling) in TrainingPeaks if you use a GPS unit and a heart rate monitor (HRM) on runs and a power meter (PM) and HRM on rides.

  1. Click the download button below to get a template spreadsheet and chart I created as a helpful visual.
  2. Go to the detail view of each aerobic zone (HR zone 1-2) run or segments of runs over the past 2-4 weeks and record the EF and Pa:HR values and date of workout in the appropriate columns of the spreadsheet you downloaded.
  3. Repeat in the bike sheet for your rides in HR Z1-2 over the past 2-4 weeks, this time using Pw:HR for cardiac drift (decoupling).

In Strava

There are a bit more calculations involved in Strava to find EF.  Luckily, I made a spreadsheet that helps you get to the answer quickly.  Download below, then follow these steps:

  1. Go to each run workout over the past 2-4 weeks that were in your HR Z1-2 and find the analysis graph and record your GAP (graded average pace, same as NP) in the min and sec columns in the spreadsheet.
  2. Record the HRavg for each run in the appropriate column.
  3. You could find your cardiac drift in Strava, but it’s quite a bit of analysis and calculations at this point.  If there’s enough interest and I have time, I might make a software tool to automatically calculate it.

If you have any questions or want me to help with the data analysis and interpretation, send me a message and I’ll be glad to discuss.